High Frequency of Normal Response during GH Stimulation Tests in Patients with Ectopic Posterior Pituitary Gland: A Source of False-Negative Diagnosis of Pituitary Insufficiency

Abstract

Aims: To report false-negative normal growth hormone (GH) peak response in patients with ectopic posterior pituitary gland (EPP) identified with a simplified magnetic resonance imaging (FAST1-MRI). Methods: We analyzed 75 EPP patients with short stature and reduced growth velocity. Sagittal-T1 imaging (thickness: 2 mm and gap: 0.2 mm) without gadolinium administration was used. A GH peak of ≥5 ng/ml after clonidine or insulin stimulation was considered normal. Results: Normal GH response was observed in 15 of 75 (20%) patients [mean (SDS) peak = 8.2 (4.1) ng/ml]. Age at diagnosis [6.5 (3.0) years vs. 7.8 (4.1) years], gender (10 males/5 females vs. 44 males/16 females), pubertal stage (14 prepubertal/1 pubertal vs. 51 prepubertal/7 pubertal), and target height [-0.4 (0.6) vs. -0.4 (0.9)] were recorded. The perinatal history did not differ between responsive and nonresponsive patients. There was a trend to more frequent multiple hormone deficiency in nonresponsive when compared with responsive patients [3/15 (20%) and 31/60 (51.7%), respectively (p = 0.055)]. Height at diagnosis was lower in nonresponsive patients (p = 0.042). No significant difference in the IGF1 levels (p = 0.598) was observed between the groups. Conclusion: Normal GH values after stimulation tests do not exclude EPP-associated GH deficiency. A simplified fast acquisition sagittal-T1 MRI protocol investigation included at the initial diagnostic approach is able to prevent misdiagnosis of GH deficiency in patients with short stature.

Pituitary Stalk Interruption Syndrome: Report of Two Cases and Literature Review

“…A recent study found that a GH response > 5ng/mL after insulin or clonidine stimulation is found in 20% of patients with EPP, so MRI imaging was proposed as a first line diagnostic approach of GH deficiency in these patients (41). Moreover, growth hormone deficiency may not be so evident in the first few years of life.…”

Testes farmacológicos de estímulo de GH em crianças e adolescentes: análise dos exames realizados no HCFMRP-USP nos últimos 15 anos

“…Observou-se que, entre os pacientes com alterações na RNM que justificariam um hipopituitarismo, 24% não manifestavam deficiências hipofisárias.A progressão desses pacientes nas consultas seguintes não foi levantada, de forma a avaliar se em algum momento posterior esses pacientes evoluíram com deficiências hipofisárias, o que poderia alterar esta proporção. Um estudo retrospectivo conduzido porKochi et al (2016) avaliou 75 crianças referenciadas por BE e que apresentavam neurohipófise ectópica, e constatou-se que 20% dessas crianças apresentavam pico de GH estimulado normal em testes de clonidina e ITT (média de 8,2 ng/mL, ponte de corte considerado para DGH foi <5 ng/mL e a dosagem de GH sérico foi feita por IQMA)83 , o que reforça nosso achado e sugere que um resultado normal no teste de estímulo farmacológico de GH não necessariamente dispensa a realização de RNM.Por fim, em relação aos diagnósticos finais estabelecidos, observou-se que as causas englobadas pela BE isolada (BE familiar e/ou constitucional e BE idiopática), conforme proposto por Collett-Solberg et al2 , correspondem à maioria dos diagnósticos estabelecidos, somando uma proporção de aproximadamente 35%. Por sua vez, as condições associadas a alterações do eixo somatotrófico (DGH isolado e associado a múltiplas deficiências hipofisárias) correspondem a aproximadamente 26% da amostra.…”